The present invention relates to self-service fuel pumping stations where the pump can be operated by a number of parties, each of whom has an individual operating key or card.
In recent years, self-service fuel pumping stations have become increasingly popular. Not only is there a savings in that the station does not have to be attended during normal working hours, but there is the advantage that fuel can be made available on a seven day a week, 24 hour basis.
In a typical self-service station, there are a number of subscribers, each of whom has an individual access key or card to operate the fuel pump. The fuel pump itself is provided with a number of key slots, one for each of the subscribers who has access to the station, or a single card reader. When an individual wishes to pump fuel, he first inserts his key or card into the particular key slot which is assigned to him. When he turns the key, power is supplied to the fuel pump to cause it to operate. The person then takes the nozzle to the tank to be filled, inserts the nozzle in the tank opening, and operates the nozzle valve to cause fuel to flow into the tank.
So that there can be an accounting for each subscriber for the fuel he pumps, there is an individual counter or meter for each key slot. Each counter keeps a total of the fuel pumped due to operation of its related key slot and the subscriber is billed periodically in accordance with the reading on the counter.
One of the problems of such self-service stations is the possibility of the person pumping fuel without this being registered on the counter. This generally occurs where there is a malfunctioning of the pulsing device, either through a mechanical or electrical failure of the component or from deliberate tampering with the pulsing device. As a precaution, many self-service stations have the pumping unit equipped with a timer which causes an automatic shut off of the pump if the pulsing device does not operate. This occurs in the following manner. When the person initially inserts his individual key or card to cause the pump to operate, the timing device is triggered. This timing device is also responsive to the pulsing device, and if the timer does not detect the pulses from the pulsing device within a predetermined time period beginning from the insertion of the key or card, the timing device shuts off the pump.
However, the time period from the insertion of the key or card to the sensing of the pulses cannot be made too short. For example, let's take the typical situation where a person might be filling the tank of a vehicle. The person first inserts his key, then takes the nozzle from the pump, walks to the location of the tank opening in the vehicle, loosens the gas cap, and then begins pumping. The present time period of the timing device must allow for the amount of time that it takes to perform the steps. Otherwise the person has the annoyance of the premature shut off. A more serious situation is where the inlet to the tank is possibly on an upper part of the vehicle so that the person must climb on top of the vehicle to fill the tank. Therefore, the timing device is usually made to respond where there is a lapse of about sixty seconds from the delivery of power to the pump and the sensing of the pulses.
Even with the timing device, it is possible for the person to obtain substantial amounts of fuel without this being registered on the counter by "milking" the pump. First, let's assume that the pulsing device in inoperable, either by tampering or accidental failure of some component. The person inserts his key and immediately starts pumping fuel. After about sixty seconds, the timing device shuts off the pump. The person leaves the nozzle in the tank inlet, and removes the key from the slot. After a short period of time during which the timing device automatically resets itself (e.g. about one second), the person again inserts the key into his individual slot and then immediately opens the valve at the nozzle to pump more gas for a period of about sixty seconds. These steps are repeated a number of times until a substantial amount of fuel has been "milked" from the tank, all of this being accomplished without any recording on the counter.
Thus the setting of the timing device is a compromise, and as a practical matter not at all the best compromise. It must be set for a sufficiently long period of time to permit the person to begin pumping fuel without a premature shut off. Yet it is desirable to have it short enough to prevent the "milking". It is to this problem that the present invention is directed.
A search of the patent literature discloses a number of patents relating generally to self-service pumping stations. For example, U.S. Pat. No. 3,099,366, Reilly, discloses a system where there are individual meter read-outs, total meter read-outs, and also meter tickets to be checked against the meter readings. Magnetic counters are activated by electrical pulses. Other systems are shown in U.S. Pat. No. 2,712,885, Winship; U.S. Pat. No. 2,995,275, Brice; and U.S. Pat. No. 3,497,107, Tatsuno.
U.S. Pat. No. 3,510,630, Ryan et al, provides an accounting system for such a self-service station where different types of fuel are taken from different sources at the station.
In view of the foregoing, it is an object of the present invention to provide an apparatus and method to effectively prevent any substantial amount of fuel being taken from the self-service station without this being recorded, and also to permit fuel to be delivered conveniently without premature shut off.